Aidan J. Brock

Interactions between Chitosan and Alginate Dialdehyde Biopolymers and Their Layer-by-Layer Assemblies

Biopolymers are researched extensively for their applications in biomaterials science and drug delivery including structures and complexes of more than one polymer. Chemical characterization of complexes formed between chitosan (CHI) and alginate dialdehyde (ADA) biopolymers established that while electrostatic interactions dominate (as determined from X-ray photoelectron spectroscopy (XPS)) covalent cross-linking between these biopolymers also contribute to their stability (evidenced from immersion in salt solution). It was furthermore found that imine bond formation could not be directly detected by any of the techniques XPS, FTIR, (1)H NMR, or fluorescence. The layer-by-layer assemblies of the biopolymers formed on silica colloids, glass slides, and alginate hydrogel beads were evaluated using XPS, as well as zeta potential measurements for the silica colloids and changes to hydration properties for the hydrogels. It was found that the degree of oxidation of ADA affected the LbL assemblies in terms of a greater degree of CHI penetration observed when using the more conformationally flexible biopolymer ADA (higher degree of oxidation).

Co-Crystallisation of 1,4-Diiodotetrafluorobenzene with Three Different Symmetric Dipyridylacetylacetone Isomers Produces Four Halogen-Bonded Architectures*

The co-crystallisation behaviour of three symmetrical dipyridylacetylacetone ligands (1,3-di(2-pyridyl)-1,3-propanedione (o-bppdH), 1,3-di(3-pyridyl)-1,3-propanedione (m-bppdH), and 1,3-di(4-pyridyl)-1,3-propanedione (p-bppdH)), with the linear halogen-bond donor 1,4-diiodotetrafluorobenzene (1,4-DITFB) has been investigated. The reaction of these components under ambient conditions in a 1 : 1 stoichiometry produced four halogen-bonded assemblies ([o-bppdH·1,4-DITFB, [m-bppdH·1,4-DITFB], [2(m-bppdH)·1,4-DITFB], and [p-bppdH·1,4-DITFB]). The combination of multiple supramolecular interactions including halogen bonding, hydrogen bonding, and π-stacking produces a range of supramolecular architectures, including one-, two-, and three-dimensional motifs. The crystal structure of m-bppdH is also reported.

A three-dimensional cubic halogen-bonded network

The rational, deliberate design of supramolecular architectures is of great importance for the discovery of complex materials. A three-dimensional cubic halogen-bonded network has been prepared by combination of an octahedral metal-containing halogen bond acceptor and a linear ditopic donor. This material displays α-Po pcu topology and is seven-fold interpenetrated. This is the first neutral, metal-containing three-dimensional halogen-bonded network to be reported.

Elastically Flexible Crystals have Disparate Mechanisms of Molecular Movement Induced by Strain and Heat

Elastically flexible crystals form an emerging class of materials that exhibit a range of notable properties. The mechanism of thermal expansion in flexible crystals of bis(acetylacetonato)copper(II) is compared with the mechanism of molecular motion induced by bending and it is demonstrated that the two mechanisms are distinct. Upon bending, individual molecules within the crystal structure reversibly rotate, while thermal expansion results predominantly in an increase in intermolecular separations with only minor changes to molecular orientation through rotation.

Chapter 10:Functional Metallo-supramolecular Polyhedral Capsules and Cages

Metallo-supramolecular capsules and cages epitomise the elegant manner in which self-assembled functional materials can be designed from first principles. Not only are these materials inherently beautiful, they are useful, performing myriad functions within the spaces that they enclose. Metallo-supramolecular capsules and cages can be prepared to be charged or neutral, large or small, open or closed and often display interesting properties including notable spectrochemical, electrochemical and magnetic effects in their own right. Through encapsulation, metallo-supramolecular capsules and cages have been demonstrated to be useful agents for host–guest chemistry, binding a wide variety of guests such as anions, cations or neutral molecules (including gases) and have been shown to catalyse a number of reactions producing unusual products more efficiently. In this chapter, after briefly discussing the design of these materials and the process of encapsulation, we survey the functions performed by metallo-supramolecular capsules and cages including selective guest binding, separations of molecular mixtures, sequestration of greenhouse gases and their use as modulators of chemical reactivity.

CCDC 1489722: Experimental Crystal Structure Determination

Related Article: Li Li, Alexander R. Craze, Daniel J. Fanna, Aidan J. Brock, Jack K. Clegg, Leonard F. Lindoy, Janice R. Aldrich-Wright, Jason K. Reynolds, Feng Li|2017|Polyhedron|125|44|doi:10.1016/j.poly.2016.08.049

CCDC 849404: Experimental Crystal Structure Determination

Related Article: Qinghua Meng, Jack K. Clegg, Aidan J. Brock, Katrina A. Jolliffe, Leonard F. Lindoy, Gang Wei|2014|Polyhedron|74|113|doi:10.1016/j.poly.2014.03.002

CCDC 849405: Experimental Crystal Structure Determination

Related Article: Qinghua Meng, Jack K. Clegg, Aidan J. Brock, Katrina A. Jolliffe, Leonard F. Lindoy, Gang Wei|2014|Polyhedron|74|113|doi:10.1016/j.poly.2014.03.002